The currently available water quality monitoring systems are quite ineffective since they often measure the water quality at predetermined time intervals such as several times a day, once a week or once in a month. This means the actual testing may occur long after pollutants and other undesirable particles are already in the water flow on their way to the consumers. One problem is that the timing of the testing is not directly correlated to the actual event of the occurrence of the undesirable particles in the water flow. Another problem is that various micro-organisms and bacteria are of about the same size as other harmless microscopic particles in the water which makes it difficult to filter out such microorganisms and bacteria. There is a need for a method that effectively monitors the water quality and automatically collects the desired sample volume for further analyze when water quality/cleanness deteriorates.